CVE-2026-21911 (GCVE-0-2026-21911)

Vulnerability from cvelistv5 – Published: 2026-01-15 20:23 – Updated: 2026-01-15 20:51
VLAI?
Title
Junos OS Evolved: Flapping management interface causes MAC learning on label-switched interfaces to stop
Summary
An Incorrect Calculation vulnerability in the Layer 2 Control Protocol Daemon (l2cpd) of Juniper Networks Junos OS Evolved allows an unauthenticated network-adjacent attacker flapping the management interface to cause the learning of new MACs over label-switched interfaces (LSI) to stop while generating a flood of logs, resulting in high CPU usage. When the issue is seen, the following log message will be generated: op:1 flag:0x6 mac:xx:xx:xx:xx:xx:xx bd:2 ifl:13302 reason:0(REASON_NONE) i-op:6(INTRNL_OP_HW_FORCE_DELETE) status:10 lstatus:10 err:26(GETIFBD_VALIDATE_FAILED) err-reason 4(IFBD_VALIDATE_FAIL_EPOCH_MISMATCH) hw_wr:0x4 ctxsync:0 fwdsync:0 rtt-id:51 p_ifl:0 fwd_nh:0 svlbnh:0 event:- smask:0x100000000 dmask:0x0 mplsmask 0x1 act:0x5800 extf:0x0 pfe-id 0 hw-notif-ifl 13302 programmed-ifl 4294967295 pseudo-vtep underlay-ifl-idx 0 stack:GET_MAC, ALLOCATE_MAC, GET_IFL, GET_IFF, GET_IFBD, STOP, This issue affects Junos OS Evolved:  * all versions before 21.4R3-S7-EVO,  * from 22.2 before 22.2R3-S4-EVO,  * from 22.3 before 22.3R3-S3-EVO,  * from 22.4 before 22.4R3-S2-EVO,  * from 23.2 before 23.2R2-S1-EVO,  * from 23.4 before 23.4R1-S2-EVO, 23.4R2-EVO.
Severity ?
6.5 (Medium)
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.1 (High)
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/V:C/RE:M/U:Amber
CWE
Assigner
References
Impacted products
Vendor Product Version
Juniper Networks Junos OS Evolved Affected: 0 , < 21.4R3-S7-EVO (semver)
Affected: 22.2 , < 22.2R3-S4-EVO (semver)
Affected: 22.3 , < 22.3R3-S3-EVO (semver)
Affected: 22.4 , < 22.4R3-S2-EVO (semver)
Affected: 23.2 , < 23.2R2-S1-EVO (semver)
Affected: 23.4 , < 23.4R1-S2-EVO, 23.4R2-EVO (semver)
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\"subConfidentialityImpact\": \"NONE\", \"vulnConfidentialityImpact\": \"NONE\", \"vulnerabilityResponseEffort\": \"MODERATE\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}], \"affected\": [{\"vendor\": \"Juniper Networks\", \"product\": \"Junos OS Evolved\", \"versions\": [{\"status\": \"affected\", \"version\": \"0\", \"lessThan\": \"21.4R3-S7-EVO\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"22.2\", \"lessThan\": \"22.2R3-S4-EVO\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"22.3\", \"lessThan\": \"22.3R3-S3-EVO\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"22.4\", \"lessThan\": \"22.4R3-S2-EVO\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"23.2\", \"lessThan\": \"23.2R2-S1-EVO\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"23.4\", \"lessThan\": \"23.4R1-S2-EVO, 23.4R2-EVO\", \"versionType\": \"semver\"}], \"defaultStatus\": \"unaffected\"}], \"exploits\": [{\"lang\": \"en\", \"value\": \"Juniper SIRT is not aware of any malicious exploitation of this vulnerability.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"Juniper SIRT is not aware of any malicious exploitation of this vulnerability.\", \"base64\": false}]}], \"solutions\": [{\"lang\": \"en\", \"value\": \"The following software releases have been updated to resolve this specific issue: 21.4R3-S7-EVO, 22.2R3-S4-EVO, 22.3R3-S3-EVO, 22.4R3-S2-EVO, 23.2R2-S1-EVO, 23.4R1-S2-EVO, 23.4R2-EVO, 24.2R1-EVO, and all subsequent releases.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"The following software releases have been updated to resolve this specific issue: 21.4R3-S7-EVO, 22.2R3-S4-EVO, 22.3R3-S3-EVO, 22.4R3-S2-EVO, 23.2R2-S1-EVO, 23.4R1-S2-EVO, 23.4R2-EVO, 24.2R1-EVO, and all subsequent releases.\", \"base64\": false}]}], \"datePublic\": \"2026-01-14T17:00:00.000Z\", \"references\": [{\"url\": \"https://supportportal.juniper.net/JSA106010\", \"tags\": [\"vendor-advisory\"]}, {\"url\": \"https://kb.juniper.net/JSA106010\", \"tags\": [\"vendor-advisory\"]}], \"workarounds\": [{\"lang\": \"en\", \"value\": \"There are no known workarounds for this issue.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"There are no known workarounds for this issue.\u003cbr\u003e\", \"base64\": false}]}], \"x_generator\": {\"engine\": \"Vulnogram 0.1.0-dev\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"An Incorrect Calculation vulnerability in the Layer 2 Control\\n\\nProtocol \\n\\n Daemon (l2cpd) of Juniper Networks Junos OS Evolved allows an unauthenticated network-adjacent attacker flapping the management interface to cause the learning of new MACs over label-switched interfaces (LSI) to stop while generating a\\u00a0flood of logs, resulting in high CPU usage.\\n\\nWhen the issue is seen, the following log message will be generated:\\n\\nop:1 flag:0x6 mac:xx:xx:xx:xx:xx:xx bd:2 ifl:13302 reason:0(REASON_NONE) i-op:6(INTRNL_OP_HW_FORCE_DELETE) status:10 lstatus:10 err:26(GETIFBD_VALIDATE_FAILED) err-reason 4(IFBD_VALIDATE_FAIL_EPOCH_MISMATCH) hw_wr:0x4 ctxsync:0 fwdsync:0  rtt-id:51 p_ifl:0  fwd_nh:0 svlbnh:0 event:- smask:0x100000000 dmask:0x0 mplsmask 0x1 act:0x5800 extf:0x0 pfe-id 0 hw-notif-ifl 13302 programmed-ifl 4294967295 pseudo-vtep underlay-ifl-idx 0 stack:GET_MAC, ALLOCATE_MAC, GET_IFL, GET_IFF, GET_IFBD, STOP, \\n\\n\\nThis issue affects Junos OS Evolved:\\u00a0\\n\\n  *  all versions before 21.4R3-S7-EVO,\\u00a0\\n  *  from 22.2 before 22.2R3-S4-EVO,\\u00a0\\n  *  from 22.3 before 22.3R3-S3-EVO,\\u00a0\\n  *  from 22.4 before 22.4R3-S2-EVO,\\u00a0\\n  *  from 23.2 before 23.2R2-S1-EVO,\\u00a0\\n  *  from 23.4 before 23.4R1-S2-EVO, 23.4R2-EVO.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cspan style=\\\"background-color: rgb(255, 255, 255);\\\"\u003eAn Incorrect Calculation vulnerability in the Layer 2 Control\\n\\n\u003cspan style=\\\"background-color: rgb(255, 255, 255);\\\"\u003eProtocol \u003c/span\u003e\\n\\n Daemon (l2cpd) of Juniper Networks Junos OS Evolved allows an unauthenticated network-adjacent attacker flapping the management interface to cause the learning of new MACs over label-switched interfaces (LSI) to stop while generating a\u0026nbsp;\u003c/span\u003eflood of logs, resulting in high CPU usage.\u003cbr\u003e\u003cbr\u003eWhen the issue is seen, the following log message will be generated:\u003cbr\u003e\u003cbr\u003e\u003ctt\u003eop:1 flag:0x6 mac:xx:xx:xx:xx:xx:xx bd:2 ifl:13302 reason:0(REASON_NONE) i-op:6(INTRNL_OP_HW_FORCE_DELETE) status:10 lstatus:10 err:26(GETIFBD_VALIDATE_FAILED) err-reason 4(IFBD_VALIDATE_FAIL_EPOCH_MISMATCH) hw_wr:0x4 ctxsync:0 fwdsync:0  rtt-id:51 p_ifl:0  fwd_nh:0 svlbnh:0 event:- smask:0x100000000 dmask:0x0 mplsmask 0x1 act:0x5800 extf:0x0 pfe-id 0 hw-notif-ifl 13302 programmed-ifl 4294967295 pseudo-vtep underlay-ifl-idx 0 stack:GET_MAC, ALLOCATE_MAC, GET_IFL, GET_IFF, GET_IFBD, STOP,\u003c/tt\u003e \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\u003cp\u003eThis issue affects Junos OS Evolved:\u0026nbsp;\u003c/p\u003e\u003cul\u003e\u003cli\u003eall versions before 21.4R3-S7-EVO,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 22.2 before 22.2R3-S4-EVO,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 22.3 before 22.3R3-S3-EVO,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 22.4 before 22.4R3-S2-EVO,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 23.2 before 23.2R2-S1-EVO,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 23.4 before 23.4R1-S2-EVO, 23.4R2-EVO.\u003c/li\u003e\u003c/ul\u003e\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-682\", \"description\": \"CWE-682 Incorrect Calculation\"}]}], \"configurations\": [{\"lang\": \"en\", \"value\": \"This issue affects label-switched interfaces configured for VPLS. For example:\\n\\n[routing-instances \u003cname\u003e instance-type vpls]\\n[routing-instances \u003cname\u003e protocols vpls]\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"This issue affects label-switched interfaces configured for VPLS. For example:\u003cbr\u003e\u003cbr\u003e\u003ctt\u003e[routing-instances \u0026lt;name\u0026gt; instance-type vpls]\u003cbr\u003e[routing-instances \u0026lt;name\u0026gt; protocols vpls]\u003c/tt\u003e\", \"base64\": false}]}], \"providerMetadata\": {\"orgId\": \"8cbe9d5a-a066-4c94-8978-4b15efeae968\", \"shortName\": \"juniper\", \"dateUpdated\": \"2026-01-15T20:23:54.924Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-21911\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-01-15T20:51:32.531Z\", \"dateReserved\": \"2026-01-05T17:32:48.710Z\", \"assignerOrgId\": \"8cbe9d5a-a066-4c94-8978-4b15efeae968\", \"datePublished\": \"2026-01-15T20:23:54.924Z\", \"assignerShortName\": \"juniper\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


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Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.